Switch and signal control system for railroads



Dec. 9, 1941. an WIGHT 2,265,258

SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed May 26, 1939 9 Sheets-Sheet 1 IONB MNB

INVVENTOVR FlchLA.

S. N. WIGHT Dec; 9, 1941 SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed May 26, 1959 9 Shets-Sheet 2 mwm nEk. TV

if BY WTIEY Dec. 9, 1941. s. N. WIGHT SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed May 26, 1939 9 Sheets-Sheet 3 INVENTOR 5 72,. 20

ATTORNEY EHHHH m a $2 $5 W? Nu H mm nzg 3 2 w UA 0 Q: 9:;

Dec.9,1941. s N w|GHT 2,265,258

SWITCH AND SIGNAL CONTROL S YSTEM FOR RAILROADS Filed May 26, 1939 9 Sheets-Sheet 4 INVENTOR BY %Mg FlGu.1.D.

Dec. 9,-1941;

5. N. WIGHT SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed May 26, 1939 9 Sheets-Sheet 5 Ax m4 INVENTOR ATTORNEY Dec. 9, 1941.

S. N. WIGHT SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS 9 Sheets-sheaf, 6

Filed May 26, 1959 INVENTOR Z? ATTORI VEY mqdi.

S. N. WIGHT SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed May 26, 1939 9 Sheets Sheet. '7

INVENTOR 5 Q ATTORNEY S. N. WIGHT SWITCH AND SIGNAL CbNTROL SYSTEM FOR RAILROADS 9 Sheets-Sheet 8 Filed May 26, 1939 INVENTOR ATTORNE'Y 7 'Dec. 9, 1941. s. N. WIGHT I 2,255,258

SWITCH AND sxemucoumon SYSTEM FOR RAILROADS Filed May 26, 1939 9 Sheets-Sheet 9 Fl 6.3.B. USA i 4T5B 'r: s: I:

' INVENTOR aw: any

Patented Dec. 9, 1941 1" UNITED STATES FFIC-E SWITCH AN D SIGNAL CONTROL SYSTEM FOR, RAILROADS Sedgwick N. Wight, Rochester, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

ApplicationeMay- 26, 1939,; Serial No..275,923

30 Claims. 01. 246-134) This invention relatesto interlocking, systems for railroads, and it more particularly pertains to an interlocking system of the entrance-exit type now Patent No. 2,219,502 granted October 29,1940.

This application is a continuation: in part of the prior application Sen No; 245;384,-filed December 13, 1938.

The entrance-exit type interlocking system provided by this invention is also to be considered as an improvement over prior applications of A. Langdon, Ser. .No. 119-,64l=, filed J anuary 8, 1937, and Patent No; 2,148,865, dated February 28, 1939,, and no claim is made herein tosubject matter disclosed in those applications.

In governing trafiic over complex track layouts by the entrance-exit system for controlling track switches and signals, an operator in a control office can cause the setting up of each of the various routes by actuating a control button on a control panel for each end of each route desired to be set up. The controlbutt'ons are generally located on a miniature track diagram on the control panel which corresponds to the track layout. for which the interlocking system is.pro-

vided. The relative location of the buttons on the miniature track diagram corresponds to the relative location of the signals of the track layout.

To facilitate the disclosure of the present invention, eachgroup of track switches providing" routes between entrance and exitpoints between which no intermediate signals are included, is conveniently called an interlocked group. Thus, in setting up a route from one end ofthe interlocking. plant to the other past intermediate signals, the complete route set up extends through a plurality of interlocked groups. The setting up of aroute extending. through a plurality of interlocked groups by actuation of the control buttons for the extreme ends only for that. route, is conveniently called end-to-end or through route control.

When an entrance point is designated by the actuation of a button for that point, in accordance with the entrance-exit system disclosed in the above mentioned Langdondisclosures, route selector relays are so positioned for each track switch included in each possible route emanating from. that point, that those relays select. the

pick-up circuits for switch: control relaysfor the various track switches in such a manner that the. actuation of a button for the. exit point for any one of those routes causes the proper posttioning of the track switch s rorset ne una route between the designated entrance and exit points. In other words, the routeselector relays are positioned response to the actuation of the button for the entrance point, andthe switch control relays are positioned, in accordance with their pick-up circuits selected by the route selector relays, in response to the actuation of the button for the exit point. Route selector relays are pickedrup only for track switchesthat are trailed by traffic in thedesignated direction. The circuits are so interlocked that no route canbeset up which conflicts with a route already established.

One object. of the present-inventionis to pro-- vide, anentrance-exit interlocking system havi'ng pick-up circuits as selected or pro-conditioned by the route selector relays. The switch control relays are picked up successively, starting withthe relay for the trackswitch nearest the exit point designated; and the responsecf: the completion network for each interlocked group causes the picking up of an entrance relay for that group, that relay being maintained picked up dependent upon the passage of a train or manual restoration. The picking up of such an entrance relay provides pickeup energy for the next exit relay toward the entrance: relay for the designated entrance point. Thus, the completion network builds up through each interlocked group untilthe-switchcontrol relays arepositioned for the entire through route between the designated entrance and exit points.

Another object of thisinvention is to provide means by which any particular one of several optional routes can be predetermined to be pre-- fer-red. Suchpreference is required in practice, for example, where a high speed track switch common to several routes is desired to be used when available, in preference. to lower speed selector relays. That is, it can be predetermined:

In response tothe actuation that a route selector relay for each track switch is to be picked up only when that track switch must be normal for the route initiated. If the circuits are provided in this manner, the optional route diverging nearest the entrance point is given preference. It can be predetermined that a route selector relay for each track switch is to be picked up only when that track switch must be reverse for the route thus initiated. If the circuits are provided in this manner, the optional route diverging nearest the exit point is given preference.

track switches are to be normal, or when their track switches are to be reverse, or some combination of normal and reverse selection, it is possible in practice to predeterminethat preference is given to any particular one optional routes.

Where a track switch is included in a reverse position in a preferred route emanating from a particular entrance point, and that track switch is included in a normal position in a preferred route emanating from another entrance point, for traffic in the same'direction, an auxiliary route selector relay is used in order to provide the desired preference for setting up routes associated with each of those entrance points. A further object of this invention is to provide a limitation of the end-to-end control in such a manner that an operator can set up any route by end-to-end operation, except a particular route which would allow a train to leave the interlocking plant against the normal direction of trafiic. To set up that particular route against the normal direction of trafilc an operator must actuate the entrance and exit control buttons for the particular interlocked group at that end of the interlocking plant. Thus, the chance of an operator inadvertentlysending a train out of the interlocking plant against the normal direction of traffic because of the actuation of the wrong exit button, is reduced to a minimum.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

p In; describing the invention in detail, reference will be made'to the accompanying drawings, in which like reference characters designate corresponding parts throughout the several illustrations,- similar letter reference characters being used to designate parts of a similar nature which are generally made distinctive by preceding numerals, and in which:

- Figs. 1A, 1B and 10, when placed side by side above Figs. 1D, 1E and 11'" respectively, illustrate the self-wlecting network provided for this particular embodiment of the present invention;

Fig. 2 illustrates certain typical circuits relative to the track switch and signal controls; and --Figs. 3A and. 313, when placed side by side, illustrate the track layout and signal controls for this embodiment of the present invention.

' In considering various parts of a similar nature from time to time during the disclosure, reference is made in a general manner to those parts by letter reference characters without their preceding numerals. It is to be understood that such a reference applies to any parts designated in the drawings by reference characters that are similar except for numerals associated therewith. The various parts and circuits constituting the embodiment of the present-invention have been of several Thus, by providingthat the route selector relays are picked up when their shown diagrammatically and certain conventional illustrations have been employed for the purpose of simplifying the illustration and facilitating in the explanation of the invention. The drawings are made more for the purpose of facilitating the disclosure of the invention as to the principles involved and the mode of operation, than for the purpose of illustrating the specific construction and arrangement of parts that would be employed in practice. Thus, the various relays and their contacts together with control buttons and other apparatus are illustrated in a conventional manner, and symbols are used to indicate connections to the terminals of batteries or other sources of electric current instead of showing all of the wiring connections to those terminals.

The symbols and are employed to indicate the positive and. negative terminals respectively of suitable batteries, or other sources of direct current; and the circuits with which those symbols are used always have current flowing in the same direction. If alternating current is used instead of direct current, the symbols should be considered to represent the instantaneous relative polarities applied to the circuits. It is to be understood that certain of the various circuits can be energized from a common battery and that several batteries can be provided where required in practice.

To facilitate in the disclosure of the present invention, various relays and circuits are shown induplicate on various pages of the drawings, and those relays and circuits shown having corresponding reference characters are to be considered identical.

Apparatus Track layout-With reference to Figs. 3A and 313, two parallel tracks have been illustrated as connected together at various points by crossovers having track switches 2TSA, 2TSB, 3TSA, 3TSB, ATSA and GTSB.

The track switches are positioned by power operated switch machines which can be of any suitable type such, for example, as the switch machine shown in the patent to W. K. Howe, Patent No. 1,466,903, dated September 4, 1923. The motors of the switch machines can be controlled in any suitable manner, such, for example, as in the patent to W. H. Hoppe et al., Patent No. 1,877,876, dated September 20, 1932. If the switch machine motors are controlled in accordance with that Hoppe et al. patent, the relay OR of that patent is controlled by the relay WZ illustrated in Fig. 2 of the present disclosure.

In order to simplify the present disclosure only one switch machine SM has been shown for each crossover, because the track switches for both ends of the crossovers should always assume corresponding positions. Thus, switch machine ZSM has been provided for positioning track switches 2TSA and ZTSB, switch machine 33M has been provided for positioning track switches 3TSA and ZTSB and switch machine 43M has been providedfor positioning track switches 4TSA and 4TSB. It is to be understood that a separate switch machine SM can be provided for governing each track switch in accordance with the requirements of practice.

A polar neutral relay WP is provided for each crossover for repeating the locked position of the track switches in correspondence with the locked position of the switch machine. That is, relay ZWP, for example, is energized with one polarity when the switch machine ZSM is in a normal lockedposition and the. track switches ZTSA and ZTSB. are locked normal, and that: relay is energi'zed with the opposite polarity when switch machine ZSM is in a reverse locked position and track switches ZTSA and 2TSB are locked reverse. Relay ZWP is dropped away whenever either of the two above conditions are not completely satisfied. The control circuits for the relays WP are selected to provide such a mode of operation by point detector contact mechanisms such as the type shown, for example, in the patent to C. S. Bushnell, Patent No. 1,517,236, dated November 25, 1924.

Signals III, II, I4 and 15 have been provided for governing east bound traflic, to the right, and signals l2, l3, l6 and I! have been provided for governing west bound traflic, to the left.

The signals have been illustrated as being of the Searchlight type. The searchlight type signals can be of a type such as is shown, for example, in the patent to O. S. Field, Patent No. 1,835,150, dated December 12, 1931. Each of the signals illustrated in this disclosure is provided with contacts closed only when the signal is at stop, as shown in that Field patent, for energizing a signal at stop repeater relay M associated with that signal. The signals are considered to provide a normal-at-stop red indication and a clear green indication. It is also to be understood that a yellow indication for caution can be provided if such indication is required in practice, and that other types of signals could as well be employed in accordance with the present invention, such, for example, as signals having individual color lamp units or signals of the semaphore. type.

The track layout has been divided into track sections by the usual insulated joints to provide the usual track circuits for the track relays. Track sections 6, 'l, 8 and 9 have been shown as having associated therewith track relays 6T, 1T, HT and ST respectively. Slow acting track repeater relays GTP, lTP, 8TP and 9TP are pro vided for track relays 6T, 1T, BT and 9T respectively. It is of course to be understood that the number of track circuits can be varied in accordance with the requirements in practice from the particular track circuit arrangement illustrated in the present disclosure. The track circuits are assumed to be of the usual normally energized type, and the track switches are assumed to be properly bonded to provide fouling protection, all of which details have not been shown in order to simplify the present disclosure, because those details are well known to those familiar with the art.

Control machine-The control machine provided for governing traffic through the track layout heretofore described, has a control panel upon which is constructed a miniature track'diagram (see Figs. 1A, 1B and 10) corresponding to that track layout. The miniature track diagram is provided with suitable indication means along the diagram sections respresentative of the track sections and track switches to provide necessary indications with respect to routes that have been established, the presence of trains on the sections, and the indication of the signals at the various points in the track layout. Inasmuch as this invention relates more particularly to the use of a self-selecting network in setting up the various routes, those indications have not been shown. Such indications can be provided as shown and described in the prior Hitchcock application, Ser. No. 74,709, filed April 16, 1936, and in the patent to. A. Langdon, Patent No. 2,148,865, dated February 28. 1939.

An entrance button NB is provided on the miniature track diagram for the entrance point to each route as defined at the track layout by the location of the signals. Thus, buttons IONB, IINB, IZNB, I3NB, MNB, ISNB, IGNB and IINB have been provided on the control panel as representative of entrance points at signals II), II, l2, l3, l4, l5, l6 and "respectively. The buttons are located on the miniature track diagram at positions corresponding to the positions of the signals at the track layout for governing entrance at those entrance points. Each entrance button NB is of the push-pull button type. That is, the button is biased to a normal position from which it can either be depressed or pulled out. There is an operating contact on the button which is closed when the button is depressed, and there is a normally closed contact on the button which is closed when the button is in its normal position as well as when it is depressed. When the button is pulled out, the normally closed contact is opened. The construction and contact arrangement for such a push button can be provided, for example, as shown in the application of J. F. Merkel, SerQNo. 153,720, filed August 12, 1937.

An exit button X5 is provided for the exit end of each possible route in the track layout, and the exit buttons are located on the track diagram at positions corresponding to the actual exit points in the track layout. Exit buttons IOXB, IDES, IZXB, ISXB, MXB, 15KB, IGXB and X3 are provided for exit points at signals H], II, l2, l3, [4, I5, l6 and I1 respectively. The exit buttons XB are of the self-restoring push button type, each having a contact closed only when that button is depressed.

Although separate push buttons have been illustrated for each entrance and exit point associated with each signal, it is to be understood that other forms of control switches could as well be used for those points, and that the entrance and exit buttons for each signal location could as well be combined into a single control switch having distinctive positions to provide the selection of the circuits necessary in accordance with the present invention. It is also to be understood that the distinctive entrance and exit control contacts can be included on one push button with circuit means provided for distinguishing between the entrance and exit operations in a manner such as is shown, for example, in the Preston application, Ser. No. 183,499, filed January 5, 1938.

A switch control lever SML is provided on the control panel for each crossover, as is typically shown in Fig. 2 for governing track switches iTSA and 4TSB, the lever eSML having a normal center position. a left hand position for operating the associated track switches to a normal position, and a right hand position for operating the associated track switches to a reverse position. Contacts are provided on the lever for each of those positions.

System de'oices.With reference to Figs. 1A, 1B, 1C, 1D, 1E and IF, each of the entrance buttons NB has associated therewith an entrance repeater relay NR which is picked up in response to the depression of that entrance button, and maintained energized dependent upon the passage of a train, or the actuation of a button for manual restoration to normal.

An exit relay X8. isprovided for each exit point in the track layout, and that exit relayis picked up when a routeis set up having an exit point with which that relay is associated. Each relay XR is maintained picked up dependent upon the entrance relay NR for the route with which that exit point is associated.

A relay 'AY or BY is provided for each of the track switches for initially selecting the position of that track switch in accordance with the defining of each entrance point by the depression' of an entrance button. Relays ZAY, 3AY and 4A! have been illustrated as being associated with track switches 2TSA, 3TSA and ATSA respectively, and relays ZBY, 3BY and 4BY have been illustrated as having been associated with track'switches 2TSB, STSB and lTSB respectively,

The relays AN, BN and R are provided for causing the operation of the track switches in accordance with routes defined by an operator by the operation of buttons for entrance and eXit points. Relays ZAN, SAN and 4AN are provided for causing the operation of the track switches of crossovers 2ts, 31's and Ms to a normal position in accordance with the setting up of routes including that position for the track overs Zts, Sis and 413s respectively to reverse 5 positions. The relays AN, BN and Rare picked up, in accordance with pick-up circuits selected by the Y relays, upon the designation of an exit point during the setting up of a route.

A slow release relay XP is associated with the entrance and exit relays provided for each in-- termediate signal for the purpose of setting up routes initiated by end-to-end control.

Each of the detector track sections is provided with a normally energized lock relay L as is typi cally shown in Fig. 2 of the accompanying drawings, relays 8L and BL having been provided for the detector track sections associated with track switches GTSA and 4TSB. The control circuits for the relays L have been shown as including contacts of route locking relays ES and WS which are provided for the various track sections in accordance with the requirements of practice. Inasmuch as it is contemplated that such route locking relays ES and WS be controlled as shown a in prior applications, the circuits for those relays have not been shown as reference can be made to other applications for the manner in which they are controlled, such as the patent to A. Langdon, Patent No. 2,148,865, dated February 28, 1939. If approach locking is to be used as well as route locking the relays ES and WS can be controlled in a manner similar to that shown for relays bearing similar letter reference characters in the patent to C. F. Stoltz, Patent No. 2,115,511, dated April 26, 1938, It is to be understood that other forms of route and approach locking can as well be used with the entranceexit system provided by the present invention.

A normally energized lock repeater relay LS is provided for each crossover as is typically shown in Fig. 2 of the accompanying drawings, in which relay 4LS is shown as a repeater of the relays L provided for that crossover.

A polar neutral switch control relay WZ is iii) provided for controlling the switch machines for each crossover in accordance with the position of the switch control relays AN, BN andR for that particular crossover. Inasmuch as each relay WZ has a similar mode of operation, only the detail circuits for relay AWZ has been shown, those circuits being typical of the circuits provided for the relays WZ associated with the other crossovers included in the track layout.

Correspondence relays NCR and RCR are provided for each crossover for repeating the position of the track switches in correspondence with the position of the relays AN, BN and R for those track switches. Relays ANCR and 4RCR have been shown as typical of the correspondence relays provided for each of the crossovers.

A signal control relay G (see Figs. 3A and 3B) is provided for governing each signal, each relay G being energized only when a route has been completely established having that signal as an entrance point.

Having thus considered the apparatus provided in accordance with the present invention, the mode of operation of th system is hereinafter disclosed more in detail in considering various typical operations of the system.

Operation Normal conditions.The normal conditions of the system are considered as those conditions which exist when the track sections illustrated are unoccupied, the signals are all at stop, and when there are no entrance or exit points defined by the operation of buttons for those points. An operator is informed of such normal conditions by the various indicator lamps (not shown) which are extinguished under such conditions to provide a normally dark board with respect to the illumination of the indicator lamps.

Under normal conditions the track switches are in their last operated positions, which, for illustration of the present disclosure, has been assumed to be the positions providing through routes on each of the parallel tracks.

The lock relays L are normally energized as is typically shown for relays 8L and 9L (see Fig. 2). A circuit is closed for the energization of relay 8L from through a circuit including front contact 24 of relay 8T, front contact 22! of relay SES, front contact 222 of relay BWS, winding of relay 8L, and front contact 25 of relay 8L, to A circuit for maintaining relay 53L picked up under normal conditions is closed from through a circuit including front contact 26 of relay 9T, front contact 223 of relay 9E8, front contact 224 of relay 9W5, winding of relay 9L, and front contact 21 of relay 9L to With. the lock relays L in a picked up position, a circuit is closed, under normal conditions, for each of the lock repeater relays LS, as is typically shown by the circuit for relay 4LS closed from through a circuit including front contact 28 of relay 8L, front contact 29 of relay 9L, back contact 30 of relay WVZ, and winding of relay 4L8, to

In accordance with the last operated positions of the track switches, as illustrated in Figs. 3A and 3B, the correspondence relay NCR for each of the crossovers is normally energized as is typically shown for relay GNCR (see Fig. 2). Relay ANCR is energized under such conditions by a circuit closed from through a circuit including back contact 3! of relay 4R, winding of relay 4NCR, polar contact 32 of relay 4W1 in a right hand position, and front contact 33 of relay liWP, to

access-s .Self-selectingnetwoflc.-It has been heretofore pointed out that the route selector relays AY and BY are so positioned for each track switch included in each route emanating from a designated entrance point, that they select the pickup circuits for switch control relays in such a manner that, when the picking up of thoseswitch control relays is rendered effective by the actuation of an exit button, the track switches are properly positioned for a route between the designated entrance and exit points.

The control circuits for the route selector relays AY and BY are so provided that those relays are picked up only when the track switches with which they are associated are trailed by trafiic' in the direction governed by the signal for the designated entrance point. Furthermore. the circuits for each of the route selector relays AY and BY are provided in such a manner that a route selector relay is picked up only if the re-, quired position of that track switch to b trailed is to be a particular predetermined position. That is, the circuits for some of the route selector relays provide that they are picked up only if their associated track switches are to be trailed when in normal positions, and the cir-- cuit for another route selector relay provides that it is picked up only if that track switch is to be trailed when in a reverse position. 7

Thus, for example (see Fig. 1C), if an operator designates an entrance point at signal l4 by depressing button MNB, route selector relay 4BY remains dropped away; but if he designates an entrance point at signal [5 by depressing button I5NB, route selector relay 4BY is picked up.

To consider an example of how a route is set up within an interlocked group, assume an operator, after checking his indicator lamps to find that the proposed route is available, depresses entrance button MNB. The depression of button MNB causes the picking up of relay I4NR. by closing a circuit from through a circuit including contact 35 of button MNB. closed in a depressed position, front contact 31 of relay BT, and winding of relay I4NR, to The picking up of relay MNR. closes astick circuit for maintaining that relay picked up from through a circuit including contact 35 of button [4N1 closed in both a depressed and a normal position, front contact 38 of relay MNR, front contact 31 of relay BT, and winding of relay I4NR,

to In each of the above described circuits, back contact 83 of relay 8'I'P is connected in the circuit in multiple with front contact 31 of relay 8T to provide that the circuits can be closed again immediately upon entrance of a train into track section 8 if it is desired to set up a route at that time for a following train.

It is to be understood that the back contacts of the track repeater relays TP, connected in multiple with the front contacts of the track re-' lays T in the stick circuits for the entrance relays NR, can be eliminated in conditions encountered in practice Where it is not required that an operator be permitted to set up a route for a following train when the preceding train is occupyingjthe track section immediately beyond the entering signal to that route.

To complete the defining of a route having signal M as an entrance point, assume an operator to depress the exit button I'IXB. Relay I'IXR is then picked up when its pick-up circuit is closed from through a circuit includ ing front contact 39 of relay MNR, backcontact 40 of relay I4XR, back contact 4| of relay 4AN, back contact 42 of relay 4BN, back contact 43 of relay 4BY, winding of relay 'I IXR, back contact 44 of relay 1 'INR, and contact 45 of button I'IXR closed in a depressed position, to The picking up of relay 'HXR closes a stick circuit for that relay extending from (+),through a cir= cuit including front contact 39 of relay MNR, back contact of relay I4XR, back contact 4| of relay 4AN, back contact 42 of relay lBN, back contact 43 of relay'4BY, winding of relay IIXR, and front contact '46 of relay IIXR, to (a).

It will be noted from the description of the pick-up circuit for relay HXR that relays 4AN and 4B'N' for governing the operation of the track switches for crossover 4ts, must be dropped away before relay IIXR can be picked up, thus providing that relay I'IXR can be picked up only when the track switches for crossover 4ts can be operated to a reverse position. In other words, an exit relay XR can be picked up only when a complete route is available between the designated entrance and exit points for the route desired to be setup.

Responsive to the picking up of relay .HXR, relay 4R (see Fig. 1F) is picked up when its cir-' cuit is closed from through a circuit in-- eluding front contact 41 of relay IIXR, back contact 48 of relay 4BY, upper winding of relay 4R, back contact 49 of relay 4BN, and back contact 50 of relay 4AN, to The picking up of relay 4R causes the operation of the track switches 4TSA and 4TSB to a reverse position in a man ner hereinafter described when considering further details of the control for the track switches.

To consider another example of how the setting up of routes is accomplished within an interlocked group, assume an operator to set u a route from signal I 5 to signal I! when that route is available, and the system is initially under the normal conditions shown and described. a

In response to the depression of button I5NB (see Fig. 1C), relay |5NR is picked up when a circuit is closed of a similar character to that circuit described for the picking up of relay MNR. Relay ISNR, when picked up, is maintained picked up by a circuit similar to the stick circuit described in detail for relay I 4NR. l

The picking up of relay 1 5NR, under such conditions, causesthe picking up of relay 4BY- when a circuit for that relay is closed from through a circuit including front contact 5! of relay ISNR, back contact 52 of relay I5XR, back gontact 53 of relay, AR, and winding of relay 4BY,

The picking up of relay 4BY allows the picking up of relay I'IXR when its circuit is closed upon the depression of the exit button I'IXB by an operator, from through a circuit including front contact SI of relay IENR, back contact 5-? of relay ISXR, back contact 53 of relay 4R, front contact 43 of relay 4BY, winding of relay HXR, back contact 44 of relay i'lN'R, and contact of button IIXB closed in a depressed position, to The closing of front contact 46 of relay ITXR provides stick energy for the circ'uitjust described to maintain relay" I'IXR picked up after button I IXB is restored to normal.

When relay ITXR is picked up, after entrance and exit points have been defined by the operator'as being at signals I5 and I! respectively, a pick-up circuit is closed for relay 4BN (see Fig. 1F) from through a circuit including front contact 41 of relay ITXR, front contact 48 of relay 4BY, upper winding of relay 4BN, and back contact 54 of relay 4R, to

' By describing the mode of operation ofthe self-selecting network for setting up a route over crossover dts'requiring its track switches in a reverse position, and by describing the mode of operation in setting up a route requiring track switch ATSB to be normal, the use of the route selector relay 4BY to select between relays AR and 4BN has been illustrated; that is, relay 4R. is energized when relay I'IXR. is picked up if relay 4BY is in a dropped away position, and relay 4BN is energized when relay I'IXR is picked up if relay 4BY is in a picked up position. Such mode of operationis characteristic of this entrance-exit system, irrespective of the number of track switches included in each route to be set Switch controls.After considering the mode of operation of the system for setting up routes within an interlocked group, consideration is now given to the means provided for controlling the track switches in accordance with the picking up of the switch control network relays AN, BN and R, and in accordance with the operation of an auxiliary switch control lever SML provided for each crossover. Inasmuch as the track switches for each crossover are controlled in a similar manner, many of the details for the switch control have been shown only for crossover 4ts. It is to be understood that the circuits shown for crossover fits are typical of the circuits provided for governing the track switches for each of the other crossovers included in the track layout, and it is also to be understood that similar circuits are provided in practice, as required, for governing single track switches.

With reference to Fig. 2, assume relay 4R. to be picked up in setting up a route as heretofore described, for example, from signal I4 to signal [1. The picking up of relay 4R, with relay 8L, 9L and 4LS picked up as described when considering the assumed normal conditions, closes a circuit for the energization of the lower winding of relay 4WZ from through a circuit including front contact 28 of relay -8L, front contact 29 of relay 9L, front contact 55 of relay ER, and lower Winding of relay 4WZ, to The picking up of relay 4WZ, due to such energization, causes the operation of the polar contacts for that relay to a left hand position, and the energization of the switch machine 4SM to operate the associated track switches to a reverse position. Such energization is efiected upon the closing of an obvious circuit including front contacts 56 and 51 of relay 4WZ.

The picking up of relay 4R, in setting up the assumed route, causes the dropping away of relay 4NCR by opening its circuit at back contact 3|, thus relay 4LS is maintained picked up after relay 4WZ is picked up to open its pick up cirsuit at back contact 30, by a circuit closed from through a circuit including front contact 28 of relay 8L, front contact 29 of relay 9L, back contact 58 of relay 4RCR, back contact 59 of relay 4NCR, front contact 60 of relay lLS, and winding of relay ILS, to

As soon as the track switches GTSA and 4TSB have been locked in their reverse. positions in setting up a route from signal M to signal I I, the relay 4WP is picked up when energized with a polarity to operate its polar contacts to a left hand position, and the picking up of that relay closes a circuit for relay 4RCR, from through a circuit including back contact BI of relay IAN, back contact 62 of relay 4BN, winding of relay dRCR, polar contact 32 of relay QWP in a left hand position, and front contact 33 of relay 4WP, to The picking up of relay 4RCR, due to such energization, causes the dropping away of relay 4LS by opening its stick circuit at back contact 58. The dropping away of relay 4LS closes the signal control circuit for signal M as is hereinafter described in considering the detail of the signal control circuits.

When relay 4WP is dropped away as soon as either of the track switches ETSA and 4TSB have been unlocked from their normal position, a stick circuit is closed from relay 4WZ from through a circuit including back contact 63 ofrelay 4WP, front contact '64 of relay 4W2, polar contact 65 of relay 4WZ, in a left hand position, and lower winding of relay 4WZ, to Such stick circuit provides that relay 4W2 is maintained picked up to complete the operation of the switch machine, irrespective of the dropping away of relay 4R, in case an operator cancels the proposed route before the switch machine ISM has completed its operation.

A similar mode of operation is effected when the track switches are operated from a reverse to a normal position. For example, assume a route to be initiated from signal l5 to signal I! when the normal conditions of the system exist as described. The picking up of relay 4BN in setting up such a route in a manner heretofore described, causes the picking up of relay 4WZ when a circuit is closed for the upper winding of that relay from through a circuit including front contact 28 of relay 8L, front contact 29 of relay 9L, front contact 6'! of relay 4BN, and upper winding of relay 4WZ, to The picking up of relay 4WZ with its polar contacts operated to a right hand position closes an obvious circuit at front contacts 56 and 5! for causing the operation of the switch machine 4SM to a normal position. If the switch machine 48M is already in a normal position at the time relay 4WZ is picked up, the picking up of relay 4WZ causes the dropping away of relay 4LS to close the signal control circuit by opening its circuit at back contact 30, because the correspondence relay ANCR remains picked up to hold open the stick circuit for relay 4LS at back contact 59.

If,-however, switch machine 4SM is in a reverse position prior to its energization for operation to a normal position, the picking up of relay 4BN opens the above described energized circuit for relay 4RCR to cause that relay to drop away and close back contact 58 in the stick circuit for relay 4LS to cause relay 4L8 to be maintained picked up by the stick circuit heretofore described until the track switches ATSA and 4TSB have been operated to a normal and locked position. The locking of the track switches 4TSA and 4TSB together with the switch machine 4SM in a normal position causes the energization of relay 4WP with its polar contacts operated to a right hand position to cause the picking up of relay 4NCR when its circuit heretofore describedis closed. When relay ANCR is picked up, the stick circuit for relay iLS is opened at back contact 59 to cause that relay to drop away and close the signal-control circuit.

When relay 4WZ is picked up for operating the switch machine 48M to a normal position, astick circuit is closed during the operation of the switch machine to provide that the switch machine will complete its operation, from through a circuit including back contact 63 of relay 4WP, front contact fi l of relay 4WZ, polar contact 65 of relay AWZ in .a right hand position, and upper winding of relay 4WZ, to

Each of the track switches has an auxiliary control means provided by a switch control lever SML which has a normal center position, a normal operating position shown to the right (see Fig. 2) and a reverse operating position shown to the left.

It is provided that the lock relays L can be picked up only when the auxiliary switch control lever .SML for that track switch is in a normal position. Such a mode of operation provides that the track switches can be operated only when the lock relays have had an opportunity to pick up prior to the operation of the switch control lever SML from its normal center position. Thus it is provided that the operation of the lever SML to an operating position causes the operation of the track switches only if those track switches can be positioned at the time the lever is operated. Such a means for preventing the preconditioning of track switches is conveniently called by those familiar with the art lever lock equivalent.

An example of the pick-up circuits provided for the lock relays for each of the track switches is shown in Fig. 2 in which relay 8L, for example, is picked up only when the detector track section '8 is unoccupied by a train and :lever 4SML is in its normal center position. The pick-up circuit is closed under such conditions from through "a circuit including front contact '24 of relay 8T, front contact 22i of relay BES, front contact 222 of relay 'BWS, winding of relay 8L, and contact 68 of lever 4SML in a normal center position, to

When lever 4S1VL is operated to a right hand normal operating position, at a time when the above described normal conditions of the system exist, relays 4AN and 4BN are picked up when then-center windings are energized. The operation of lever 4SML to a normal operating right handpositioncloses a circuit for relay lAN from through a circuit including contact '69 of lever 4SML'in a right hand position, center winding of relay IAN, and back contact H1 of relay @R, to In-a similar manner the closing of contact TI in 'a right hand position effectsthe energization of an obvious circuit for relay' lBN. The picking up of relays 4AN and iBN causes the energization of relay GWZ and the operation of theswitch machine to a normal locked position in the same manner as heretofore described when relay 4BN was assumed to be picked up in setting up a route by operation of the control buttons *for the entrance and exit points.

If lever iSML is operated to a reverse operating left hand position, when the above described normal conditions of the system exist, relay 4B is picked up when its obvious circuit is energized for itscenter winding upon the closing of contact 69 of lever 4SML in a left hand reverse operating position. The picking up of relay 4R under such conditions of course causes the .operation of the switch machine 4SM to a reverse position the same as described when that relay was assumed to'be'picked up in setting up a route from signal M to signal ll.

Signal controls-When each of the track switches has completed its operation in accordance with the positions required in setting up each proposed route, it has been pointed out'that the relay LS associated with that track switch is dropped away to close the signal control circuits.

"To consider an example of the signal control circuits provided for each of the signals in the track layout, assume the track switches 4TSA and 4TSB to have completed their operation to a locked reverse position in accordance with a route defined by an operator by the depression of an entrance button for signal 14 and an exit button for signal IT. When relay 4L8 has been dropped away, a circuit is closed for relay MG (see Fig. 33) from through a circuit including front contact 72 of relay I'IXR, back contact '13 of relay 4LS, back contact 14 of ,relay dNCR, front contact 15 of relay 4RCR, back contact 16 of relay 4NCR, back contact H of relay 4LS, back contact 18 of relay I 4XR, front contact 79 of relay MNR, and winding of relay 14G, to (s). The picking up of relay 14G .applies energy ,at front contacts 80 and 8| to the search light signal mechanism of signal 14 to cause that signal to display a green clear indication.

Route and approach locking.Inasmuch .as the route locking used in this embodiment of the present invention is similar to that typically shown in prior applications, the route locking relays havebeen shown only in .block form in the present disclosure (see Fig. 2). It is to be understood that the circuits by which'those route locking relays are controlled are provided as typically shown, for example, in the patent to A. Langdon, Patent No. 2,148,865, dated February 28, 1939. It is also to be understood that other forms-of route locking can as well be used, and that, if approach locking is required in practice, the route and approach locking can be provided as shown, for example, in the patent to C. F. Stoltz, Patent No. 2,115,511, dated April It is believed, however, that, for an understanding of the present invention, it is sufiicient to consider that the relays ES and WS are respectively east and west directional stick normally energized relays, there being an ES relay and a WS relay for each track section of the layout as required. The setting up of any given route causes the ES or WS relay for the proper direction to be deenergized for each track section in such route and to remain dropped away for that portion of such route occupied by, and

in advance of, each train, although the entering signal has returned to stop. These relays are then successively energized as the train leaves the track section with which they are respectively associated.

It is obvious, with reference to Fig. 2 of the accompanying drawings, that whenever eitherof the route locking relays associated with the detector track section for a particular track switch, are dropped away, the lock relay L for that track section is dropped away to cause the electric locking of that track switch to become effective.

Restoration to normaL-To consider how a signal can be restored to stop, and the parts of the system associated with the setting up of routes restored to normal at thewill of an operator, assume, for example, an operator to cause the restoration of a route set up as heretofore described from signal It to signal 11 by pulling out button MNB.

When button MNB is pulled out, the stick circuit for relay MNR is opened at normally closed contact 35 of button MNB to cause that relay to drop away. The dropping away of relay MNR, causes the dropping away of signal 001117110116- iay MG (see Fig. 313) by opening the circuit for that relay at front contact E9, and the opening of front contacts 89 and BI caused by the dropping away of relay l iG deenergizes the mechanism in signal It to cause that signal to be re stored to the position to display a red stop indication.

The dropping away of relay iiNR also causes the dropping away of relay HXR by opening the circuit for that relay at front contact 39. When relay HXR. is dropped away, the upper winding of relay GR is deenergized, due to the opening of front contact H of relay ilXR. Inasmuch as the detector track section is unoccupied at that time, the center winding of relay 4R is deenergized, thus causing that relay to drop away.

A very similar mode of operation is effected upon passage of a train, the principal difference being that the stick circuit for relay MNR is automatically opened as soon as a train accepts the entering signal Hi, instead of being opened by the manual actuation of the entrance button MNB. To consider an example of such restoration upon passage of a train, assume a route to be set up in a manner which has been described from signal 14 to signal 11, and assume an approaching train to accept signal l4 and enter track section 8.

When a train enters track section 8 and relay HT is dropped away, under such conditions, the stick circuit for relay him is opened at front contact 31 of relay 8T to cause relay MNR to drop away and cause the restoration to normal of the relays associated with the route set up including that entrance point, and the restoration of signal I4 to stop, all in the same manner as described above, except that the restoration of relay 4R to normal is delayed until the passing train has left track sections 8 and 8.

Such relay is provided in order to prevent the preconditioning of routes by maintaining an interlock in the self-selecting network. To provide such mode of operation. the center wind.- ings of the completion network relays AN, BN and R are energized whenever the track switches with which they are associated are electrically locked either by route, approach, or detector locking.

Thus, relay AB is maintained picked up under the above assumed conditions as long as the passing train occupies track section 8 because relay 8L is dropped away upon the opening of its circuit at front contact 22! of relay 8E8, and the dropping away of relay 8L closes a stick circuit for relay 4R (see Fig. 2) from through a circuit including back contact 85 of relay 8L, front contact 86 of relay 4R, back contact 81 of relay eAN, center winding of relay ER, and back contact 88 of relay 4BN, to When signal Hi is cleared for that route, the dropping away of relay SES causes the dropping away of relayQL by opening its circuit at front contact 223, and the dropping 'away of relay 8L closes a stick circuit for relay 4R from through a circuit including back contact 58 of relay 9L, front contact 95 of relay 5R, back con tact 81 of relay AAN, center winding of relay 4R, and back contact 88 of relay QBN, to

As soon as the train leaves the track section 8, relay 8L is picked up, and the stick circuit closed by that relay at back contact 85 is opened, and as soon as the train leaves track section 8, the picking up of relays ST and 5135 causes the energization of relay 9L which opens the stick circuit for relay 4R at back contact 89. Thus,

relay AB, is maintained energized until both of the detector track sections for its associated track switches are unoccupied, after which it is restored to normal, because the pick-up circuit for that relay is opened by the dropping away of the exit relay HXR at front contact 41 (see' Fig. 1F). It is obvious that the above described circuits for the center winding of relay 3R are effective for either direction of trafiic.

Having thus described the mode of operation by which a particular signal can be restored to normal, and the parts of the system associated with the setting up of a particular route restored to normal, it is to be understood that a similar mode of operation is employed for the restoration of each of the other signals included in the track layout, and for the parts of the system associated with the setting up of each of the other routes.

End-to-end controZ.-To provide that an operator need only actuate the control buttons for the extreme ends of each route to be set up, ire respective of the number of intermediate signals included in that complete route, a system is provided whereby the route initiated is selected by sectionsrin a successive order, a section being provided for each interlocked group, starting with the section for the interlocked group nearest the exit point.

To consider the general mode of operation of the system in setting up routes by end-to-end control, assume, for example, an operator to initiate the setting up of a route from signal It to signal H at a time when the normal con-, ditions of the system exist as illustrated and heretofore described.

In setting up a route from signal it to signal ll, relay iBNR. (see Fig. 1F) is picked up when the entrance button IBNB is depressed, and the picking up of relay ItNR, applies energy to the initiating network in such a manner as to feed toward the exit relays for all available exit points for routes having an entrance point at signal I6. The picking up of relay HENR causes the energization of relay lAY, the picking up of which closes a portion of the selecting network circuit for completing a circuit through to the exit relay for each available exit point. Although the general mode of operation of the system is to pick up a route selector relay Y for each track switch trailed for main line trafiic for the particular route set up, the route selector relay BAY is controlled in a different manner for purposes to be hereinafter pointed out in considering the selection of optional routes. Inasmuch as relay 3AY is not picked up in setting up a route from signal it to signal H, the initiating network circuit for each available exit relay XR can be completed after relay 4AY has picked up. Thus, an operator proceeds to designate the exit point for the proposed route by the depression of button HXB, and relay HXR is picked up as a result of such actuation.

When relay HXR is picked up, in setting up such a route, relay 2R is energized because it is selected in preference to relay ZBN by the dropped away position of the route selector relay EBY, and the picking up of relay 2R causes the energizetion of relay 3AN in preference to relay 3R because the route selector relay SAY is dropped away. After relay SANis picked up, relay QQXP is energized, and the picking up of that relay effects the energization in turn of relays i2NR and MXR respectively. Upon the picking up of relay MXR, relay |2XP is decnergized and allowed to drop away, after completing its principal purpose of causing the picking up of the entrance relay associated with signal I2, and after causing the picking up of the next exit relay I4XR. When relay I4XR is picked up, relay 4AN is energized in preference to relay 4R because the route selector relay 4AY is already picked up to select that particular relay.

Thus, the switch control relays in the completion network are positioned for the entire route designated, and the track switches with which those relays are associated are positioned in a manner similar to that which has been heretofore described as typical for the track switches associated with crossover its. After the track switches have completed their operation to positions required for such a route, the signals for each of the interlocked groups provided for governing traffic through that route are cleared, each signal being energized by circuits provided for that particular interlocked group in a manner which has been heretofore described as typical of all signal control circuits.

Having thus considered thegeneral mode of operation in setting up a route by end-to-end control, consideration will now be given to the details of the circuits which provide such mode of operation, it being assumed that the normal conditions of the system exist as heretofore described,'and that an operator proceeds toset up a route as heretofore described in a general manner from signal IE to signal II.

The actuation of button I BN'B in setting up such a route, causes the picking up of relay I BNR (see Fig. 1F) by the energization of a circuit closed from through a circuit including, contact 9! of button IBNB closed in a depressed position, front contact 92 of relay BT, and winding of relay ISNR, to The picking up of relay IfiNR closes a stick circuit for that relay from through a circuit including contact 9I of button ISNB closed when button I6NB is both normal and depressed, front contact 93 of relay I6NR, front contact 92 of relay BT, and winding of relay ItNR, to lay BTP is connected in multiple with front contact 92 of relay 8T to provide that relay IGNR can be picked up when track section 8 is occupied as well as when it is unoccupied.

Upon the picking up of relay I6NR a circuit is closed to cause the picking up of relay 4AY by the energization of a circuit closed from through a circuit including front contact 94 of relay IBNR, back contact 95 of relay I BXR, back contact 96 of relay 4H, and winding of relay 4AY, to

When an operator designates the exit point for the route being set up, by the depression of button I IXB, a circuit is closed for relay I IXR, from through a circuit including front contact 94 of relay I BNR, back contact 95 of relay I GXR, back contact 99 of relay 4R, front contact 91 of relay 4AY, back contact 98 of relay I lXR, wire I92, back contact I04 of relay IZNR, back contact I of relay I ZXR, back contact I06 of relay 3R, back contact I97 of relay 3AY, wire I08, back contact I99 of relay ZEN, back contact IIO of relay ZAN, back contact III of relay ZBY, winding of relay IiXR, back contact II2 of relay I INR, and contact H3 of button IIXB closed in a depressed position, to Upon the picking up of relay IIXR, a stick circuit is closed for that relay at front contact H4 to shunt out, in the circuit above described, contacts H2 of relay IINR and H3 of button IIXB.

Back contact 2I5 of res Upon the picking up of relay IIXR, relay 2B. is picked up when its circuit is energized from through a circuit including front contact II5 of relay II XR, back contact II6 of relay 2BY, lower winding of relay 2R, back contact II! of relay ZBN, and back contact II8 of relay 2AN, to When relay 2B is picked up, a circuit is closed to cause the picking up of relay 3AN, from through a circuit including front contact I I5 of relay I IXR, back contact I I5 of relay 2BY, front contact II9 of relay 2R, wire I20, back contact I2I of relay SAY, lower winding of relay 3AN, and back contact I22 of relay 3R, to

A circuit is closed upon the picking up of relay SAN for-the energization of relay I2XP, from through a circuit including front contact II5 of relay IIXR (see Fig. 1D) back contact H5 of relay 2BY, front contact II9 of relay 2R, wire I20, back contact I2I of relay 2AY, front contact I23 of relay 3AN, winding of relay IZXP, and back contact I24of relay I2NR, to When relay I2XP is picked up, a stick circuit is closed forthat relay to shunt back contact I24 of relay I2XR out of the circuit just described by a circluit closed from wire I25, through a circuit including front contact I26 of relay I2XP, wire I22, and back contact I28 of relay I4XR, to

A circuit is closed upon the picking up of relay -I2XP for relay I2NR, from through a circuit including normally closed contact I29 of button I ZNB, front contact I30 of relay I ZXP, front contact I34 of relay GT, and winding of relay IZNR, to A stick circuit is closed for relay IZNR upon the picking up of that relay from through a circuit including normally closed track section 8 is occupied as well as when it is unoccupied.

l The initiating circuitby which relay IIXR is maintained energized, is maintained closed during the shifting of contact I94 of relay I2NR by from contact 2|! of relay I2XP connected in multiple with back contact I04. The picking up of relay IZNR applies energy to the initiating network for energization of relay I IXR at front contact I04 the same as is done in setting up a route within that interlocked group.

Upon thepicking of relay I ZNR, a circuit is closed for relay I4XR from through a circuit including front contact 94 of relay ISNR (see Fig. 1F) back contact of relay ISXR, back contact 96 of relay 4R, front contact 9'! of relay 4AY, winding of relay I4XR, back contact I 35 of relay I4NR, wire I31, front contact I39 of relay I2NR, and front contact I40 of relay I 2XP, to The picking up of relay I4XR, due to such energization, closes a stick circuit for that relay from (71-) through a circuit including front contact 94 of relay IGNR (see Fig. 1F) back contact 95 of relay IBXR, back contact 95 of relay 4R, front contact 91 of relay 4AY, winding of relay I4XR, and front contact I4I of relay MXR, to

The picking up of relay I4XR causes the dropping away of relay I2XP by opening the stick circuit for that relay at back contact I28 (see Fig. IF) the pick-up circuit for that relay having been opened upon the picking up of relay IZNR at back contact I24 (see Fig. 1E).

Whenrelay I4XR is picked up in setting up a route from signal 16 to signal 11, relay QAN is picked up by the energization of a circuit closed from through a circuit including front contact 142 of relay MXR (see Fig. 1F) front contact I43 of relay 4AY, lower winding of relay MN, and back contact 54 of relay 4R, to

Thus, the circuits have been completely described by which the self-selecting network is positioned in setting up a route by end-to-end control, and it is believed that it can be readily understood by those familiar with the art how desired.

It may be well at this time to give some consideration to the reasons for certain of the circuit selections, and the affects of those selections on the mode of operation of the system.

It'is provided that the parts of the system associated with end-to-end control are used only while the route is being set up. That is, after each complete route is set up, the condition of the system is the same as if that route had been set up by sections from signal to signal through each interlocked group. Thus, the restoration to =normalof the system associated with a route set up by end-to-end controldseffected for each inthe locked group included in the route, the same as heretofore described for a particular route within an interlocked group.

Although a through route may be set up through several interlocked groups by merely entrance and exit manipulations for the ends of such through route, it must be restored by individually pulling the buttons NB at the entrance to each of the groups included in the through route.

Preferred route selection-It has been heretofore pointed out in a general manner what conditions are encountered in practice in connection with the selection of a preferred route of aplurality of optional routes, and the means provided by the self-selecting network for selecting a particular preferred route. A means has been pointed out in the above mentioned prior Langdon application Ser. No.'119,641, filed J anuary'8, 1'93"], and Patent'No. 2,148;865, dated February 28, 1939, whereby, of several optional routes available, the route diverging nearest the entrance point is always given preference. Consideration is now given more in detail to the means provided by this invention whereby any particular route can be given preference over a plurality'of optional routes available, irrespective of whether or not it diverges nearest the entrance or exit point.

Thus, it has been provided in the present embodiment of this invention that a route set up from signal H to signal It is set up via crossover .3ts in preference to the inferior optional route via crossover fits. Such preference is accomplished bythe control circuit for the route selector relay 3AY (see Fig. 1E) associated with track switch-3TSA. v

To consider the general mode of operation of the system by which the route from signal H to signal l fl'via crossover Sis is made preferred, the initiating network circuits can be considered to assume-a form similar in effect to the actual track layout for which the system is provided. That is, the network system feeds energy, when an entrance point is designated, for example, at signal IT, at a time when the heretofore described normal conditions of the system exist, through the initiating network circuits toward the exit relay for each available exit point. Thus, energy can be said to feed in directions corresponding to traffic through the actual track layout in the field from entrance relay l'lNR through a normal branch of the network circuits associated with crossover its to relay I5XR, and through a branch of the network corresponding with the crossover (its having its track switches STSA and vSTSB in a reverse position to exit relay IfiXR. There is also a multiple path, as there is .in the track layout from relay HNB through a branch of the initiating network corresponding to crossover Me with its track switches ATSA and iTSB in reverse positions to exit relay MXB,

.and through a branch of the self-selecting network corresponding with the normal position of the track switches associated with crossover 315s toexit relay IBXB.

The route selector relays Y, as has been heretofore pointed out, are connected in multiple in the initiating network at various points where selections are included for the track switches with which those relays are associated. Thus, a relay 4AY (see Fig. IE) is provided in the initiating network in the normal branch of the network extending from a front contact of relay 'IBNB; and when relay GAY is dropped away, the reverse branch of the self-selecting network is closed from a front contact of entrance relay HNB over the reverse branch of the initiating network circuits corresponding with crossover Its with its track switches in the reverse position, and when relay lAY is picked up, that reverse branch of the circuit is opened, and the normal branch of the circuit extending from a 'front contact of entrance relay IEiNB, to exit relay MXB, is closed.

The relay 3AY (see Fig. 1E), associated with track switch 3TSA, however, is energized from the branch of the initiating network corresponding with crossover 312s having its track switches in a reverse position. When relay 3AY is dropped away, the circuits through the self-selecting network are closed through the normal branch corresponding with thetrack including track switch 3TSA in a normal position, and when that relay is picked up, the initiating network circuits for setting up routes for west bound trafic are closed through a branch of the circuit corresponding to crossover 3138 having its track switches in reverse positions. It is thus provided that, in setting up a route from signal I! to signal Ill, the branch of the initiating circuit network is closed corresponding to the route between those designated entrance and exit points vla crossover 3ts because relay 3AY becomes energized, and the branch of the initiatingnetwork corresponding to the, route designated between signal I I and signal 10 via crossover dis is opened upon the Picking up of relay 3AY.

.Such mode of operation renders the portion of the self-selecting network corresponding with the route diverging nearest the entrance point ineffective for setting up such a route, and gives preference to the particular route for which the route selector relay Y is energized in the reverse branch of the initiating network control.

To consider details of the mode of operation by which the route from signal I! to signal I via crossover 3ts is given preference over other routes,

assume an operator to depress button I'INB at a time when the normal conditions of the system exist as heretofore described. As a result of such actuation relay IINR (see Fig, 1F) is energized by circuits closed in a manner similar to that described associated with the circuits for relay IBNR as typical, and the picking up of relay I'INR provides energy for relay 3AY by a circuit closed from through a circuit including front contact I44 of relay IINR, back contact I45 of relay I'IXR, back contact I46 of relay 4R, back contact I41 of relay IEXR, wire I49, back contact II of relay I 3NR, back contact I52 of relay ISXR, back contact I53 of relay 3BN, back contact I54 of relay 3AN, and winding of relay 3AY, to The picking up of relay 3AY'opens the normal branch of the initiating network circuit at back contact I 01.

Upon designation of the exit point for the route being set up, by the depression of button IUXB, an operator causes the picking up of relay I am, (see Fig. ID) by the energization of a circuit closed from through a circuit including front contact I44 of relay I 'INR (see Fig. 1F), back contact I45 of relay I 'IXR, back contact I46 of relay 4R, back contact I41 of relay I5XR, wire I49, back contact I5! of relay I3NR, back contact I52 of relay I3Im, back contact I53 of relay 3BN, back contact I54 of relay 3AN, front contact ID! of relay 3AY, wire I08, back contact I55 of relay 2R, winding of relay IIIXR, back contact I56 of relay IIINR, and contact I51 of button IIJXB closed in a depressed position, to The picking up of relay IBXR closes a circuit at front contact I58 to shunt contacts I5! and I56 out of the circuit heretofore described.

Upon the picking up of relay IQXR, a circuit is closed for the energization of relay 2AN, from through a circuit including front contact I59 of relay II'IXR, lower Winding of relay 2AN, and back contact I69 of relay 2R, to When relay 2AN is picked up, a circuit is closed to cause the picking up of relay 3R from through a circuit including front contact I59 of relay IBXR (see Fig. 1D), front contact IEI of relay 2AN, wire I20, front contact I2I of relay 3AY, lower Winding of relay 3R, back contact I62 of relay 3BN, and back contact I63 of relay SAN, to When relay 3R is picked up, a circuit is closed for the energization of relay I3XP from through a circuit including front contact I59 of relay IDXR (see Fig. 1D), front contact I6I of relay ZAN, wire I29, front contact I2! of relay 3AY, front contact I64 of relay 3R, winding of relay I3XP, and back contact I65 of relay I 3NR, to Upon the picking up of that relay a stick circuit is closed to maintain that relay energized until relay IEXR is picked up, from through a circuit including front contact I59 of relay IUXR, front contact IEI of relay ZAN, wire I20, front contact IZI of relay SAY, front contact I64 of relay 3R, winding of relay I 3XP, front contact I66 of relay I3XP, wire I61, and back contact H23 of relay I5XR, to

A circuit is closed for the energization of relay ISNR (see Fig. 1E), upon the picking up of relay I3XP, from through a circuit including contact I69 of button ISNB closed in a normal position, front contact ll!) of relay ISXP, front contact I14 of relay IT, and winding of relay IGNR,

to When relay ISNR is picked up, a stick circuit is closed for that relay the same as just described except that front contact I15 of relay I3NR is closed to shunt front contact I IQ of rela ISXP out of the circuit.

The initiating circuit by which relay IUXR is maintained energized, is maintained closed during the shifting of contact I 5| of relay I 3NR (see Fig. ID) by front contact 2 I 8 of relay I3XP connected in multiple with contact I5I. The picking up of relay I3NR applies energy to the initiating network for energizing relay IGXR at front contact I 5| the same as is done in setting up a route within an interlocked group.

After relay I SNR is picked up, a circuit is closed for the energization of relay ISXR, from through a circuit including front contact I44 of relay I'ENR. (see Fig. 1F), back contact I45 of relay IIXR, back contact I46 of relay 4R, winding of relay IEXR, back contact I15 of relay I 5NR, wire I16, front contact I78 of relay I3NR, and front contact I I9 of relay ISXP, to When relay ISXR is picked up, the above described stick circuit for relay IQEIQ is opened at back contact I88 to cause relay i3XP to drop away.

A stick circuit is closed, upon the picking up of relay I5XR at front contact 2 I 9 of relay I5XR, from through a circuit including front contact IM of relay I'INR, back contact I45 of relay IIXR, back contact I46 of relay 4R, winding of relay I BXR, and front contact 2 I9 of relay I5XR, to

Upon the picking up of relay I SXR, under such conditions, relay BN is picked up by the energization of a circuit closed from through a circuit including front contact I80 of relay ISXR, lower winding of relay IBN, and back contact 54 of relay 4R, to

Responsive to the picking up of relays Z'AN and GEN, the track switches associated with crossovers 225s and fits are operated to their normal positions, and responsive to the picking up of relay 3R, the track switches associated with crossover Bis are operated to their reverse positions, all in a manner similar to the condition described as typical of the system when considering the details of the switch control circuits.

After the track switches have assumed their selected positions, the signals are cleared as a result of the energization of circuits similar to a signal control circuit heretofore described as typical of the circuits provided for clearing each of the signals.

It is therefore readily apparent that, in order to give a route via a particular track switch preference over optional routes, irrespective of the location of the trackswitches in the route, the Y relay energized for that particular track switch or crossover for that particular direction of traffic is energized in the reverse control branch of the initiating network, and the reverse switch control relay for controlling that track switch is selected for energization when the Y relay is picked up.

In view of the nature of the means provided for causing a particular route to be preferred, the same system can be used in causing a particular route to be preferred over optional routes Within an interlocked group. Thus, for example, in setting up a route from signal II to signal I3, it is necessary to select between the two optional routes, one of which includes the track switches associated with crossovers Zts and 3ts in normal positions, and the other of which includes the 

